Signal system



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Patented Jan. 20, 1942 UNITED STATES PATENT OFFICE 4 Claims.

This invention relates to a system for the transmission of signals and information, or more particularly to an electrical system'by which an operator at headquarters can immediately cornmunicate information to those in attendance at a plurality of signal receiving stations.

The embodiment of the invention herein described is intended particularly for use in place of the conventional re alarm systems to transmit signals and information relating to the control of iire apparatus.

At the present time, information as to the existence of a re is transmitted to the fire alarm headquarters by one of two methods. First by operating the conventional fire alarm box which causes' a certain number of beats to be struck upon a gong in the iire headquarters, the number of beats corresponding to the location of the box operated. This signal is retransmitted by the operator at headquarters to the various fire apparatus stations. This type of signal can not be transmitted with great rapidity due to the fact that it is necessary for those in attendance at the fire apparatus stations to be able to separate the groups of digits in the number of the signal being transmitted. A certain amount of time is also consumed by the operator at headquarters in arranging his apparatus to retransmit the signal to the respective fire stations.

The second method of receiving information of a iire is by use of the telephone. Upon receiving such information, the operator at headquarters sends out a two stroke signal on the gong system which indicates to those in attend- 'ance at each fire station that there is a fire and that one man in each station is to communicate with the operator at headquatersby telephone. When the operator at headquarters is informed by a supervisory signal that someone is listening at the telephone at each fire station he then announces over the telephone system the location of the rc. Due to the constant increase in the use of telephones, the percentage of alarms received by telephone is constantly increasing.

l'I'his arrangement has certain inherent disadvantages. First, an appreciable amount of time is consumed in phoning the information to the re houses. Second, when the operator at headquarters gives the information as to the location of the re, the only man in each re station that receives this information is the one listening to the telephone in that station. Ofter during the excitement of the emergency, or because of the similarity in the names of different streets, the man receiving the information at the nre station is misinformed, or reaches the wrong conclusion as to where the fire is located, with the result often that the apparatus that is supposed to attend the re does not do so.

This invention has as a general object a cornmunication system by which the operator at headquarters can instantly communicate any information to`each re station in the city, and such information is communicated to all men in each rehouse, thereby saving an appreciable amount of time in communicating the signal, and in also accurately communicating the location of the re, or other information, so that all those in attendance at all fire houses are accurately informed.

The invention has as a further object a communication system employing a plurality of voice transmitters, and a plurality of voice current amplifiers with provision whereby the operator at headquarters may instantly connect any one of the transmitters or amplifiers into the circuit, the system also including various devices operable to at all times indicate the operating condition of the amplifiers.

The invention has as a further object a system of the type referred to, including a plurality of voice current output circuits extending to the various fire stations, or signal stations in the system, and including means for indicating at all times the electrical condition oi each of said circuits. Other objects of the invention will be readily apparent as the description of the embodiment herein shown proceeds.

The invention consists in the novel features and in the combinations and constructions hereinafter set forth and claimed.

In describing this invention, reference is made to the accompanying drawing which represents a schematic wiring diagram of a system involving my invention.

The system comprises generally a voice current amplifier to which a transmitter or microphone is connected, and the output circuit of which is connected to a plurality of outside signal circuits extending to the various rehouses. A loud speaker is arranged in each iirehouse and is connected in one of the outside output circuits.

It will be apparent, as the description of the system proceeds, that the same may be employed to communicate information to a plurality of signal stations, for example to a plurality of points about a large manufacturing plant.

' Where the system is used as a fire alarm system, it is preferably provided with two or more amplifiers I0. The amplifiers are energized by wires II, I2 connected to a suitable supply. As here shown, and in accordance with conventional arrangement of emergency signaling systems, two separate sources of supply A and B are provided. Each amplifier I may be connected to either source A or B by the double pole, double throw switches I3, I4. In the drawing, the switches I3, I4 are shown shifted to the left position whereby amplifier No. 1 is connected to the source A. A pilot lamp I5 is connected across each of the sources A and B to indicate that the respective sources are energized. and a voltmeter I6 is likewise connected across each source to indicate the potential of the current therein.

I1, IB designate a pair of microphones or transmitters, either of which may be connected to amplier I, or amplier 2, by the double pole, double throw switches I9, 2D. As shown in the drawing. the switches I5, 2D are also shifted to the left, connecting transmitter Il with amplifier No. I. Either amplifier No. I, or No. 2, may also be connected with the output circuit 2I of a high frequency radio receiver. In many cities the cars operated by the re chiefs are equipped with high frequency mobile radio transmitters, whereby the fire chiefs can communicate directly to headquarters from the scene of the fire. If switch is shifted to the central position, any such communications received from such mobile transmitters may be dispatched directly to all of the fire stations.

The plate circuit of each of the amplifiers is brought out to contacts 22, 23 respectively, and is open when the amplifiers are not in use. Either plate circuit may be closed by an operating switch 24. The arrangement is such that leg of the operating switch is connected in either plate circuit by a double pole, double throw switch 26. This switch is illustrated as shifted 'to the left position, whereby when operating switch 24 is closed. the plate circuit, of amplifier No. I, is closed by leg 25 of switch 24. Leg 2l of the operating switch is employed to close an auxiliary circuit including a pilot lamp 28. The purpose of the auxiliary circuit and the pilot lamp 28 is to give the operator a visual indication that the plate circuit of theamplier in use is closed. It will be observed that it is only necessary for the operator to close switch 24 to dispatch a message through either amplifier.

The output circuits of the amplifiers are indicated at 30 and 3i respectively. These circuits are individually connected to a circuit 32 by the double pole, double throw switch 33.

In order to simplify the operation of the system by the operator at headquarters, I prefer to arrange the switches I3, I4, I9, 20, 26 and 33 in a row and all shiftable in one direction to connect amplifier I in use. and shiftable to the opposite position to connect amplifier 2 in use. Each of the amplifiers is provided with a lament pilot lamp 34 which is connected in series in the circuit II-IZ and indicates at all times that all of the tubes in the amplifiers are energized. Each of the plate circuits includes a milliammeter 35 to indicate the condition of the plate circuit of each'amplifier. With this arrangement, the operator is constantly advised as to the electrical condition of the amplifying portion of the apparatus.

At all times, it is only necessary for the operator to close switch 24 and speak into the transmitters Il or IB. When the message is completed, the switch 24 is opened.

In fire alarm systems it is customary to provide a plurality of outside signal circuits, each circuit extending to one or more fire stations. My system is particularly weil suited to this arrangement. For purposes of illustration, I have shown two outside signal circuits C and D. Each of these circuits extend from headquarters to a plurality of re stations, circuit C being shown as extending to three re stations, and circuit D extending to two fire stations. It will be understood that there are a plurality of outside circuits in a fire alarm signal system. Each of these circuits vary in length and electrical characteristics with the result that each circuit has a different impedance. My invention includes means for matching the impedance of each outside circuit to the impedance of the output circuit 32. Each of the outside circuits C, D are connected to the circuit 32 through a line matching variable transformer 40 having a primary circuit 4I connected to the circuit 32 and including a potentiometer 42, the purpose of which is to provide adjustment to control the level of the amplified voice signal transmitted over each outside circuit.

The secondary winding 44 of the transformer is connected to the conductors 45, 46 of the outside circuit. Each of these conductors include a fuse 4l, and each is connected to a lightning arrester 48. The outside circuit, formed by the conductors 45, 45, extends to one or more signal stations such as firehcuses, and at each signal station a loud speaker 49 of suitable construction for the purpose is connected in series in the circuit. For purposes of illustration. I have shown the outside circuit C as extending to three signal stations, and the circuit D to two signal stations. However, as previously stated. there may be a comparatively large number of outside circuits and each may extend to several signal stations.

A capacity element, such as condenser 5U. is connected in one leg of the outside circuit, for example, conductor 46. A high resistance voltmeter 5I is connected across the conductors 45, 43, through high resistance elements 52. The purpose of the voltmeter 5l is to indicate the voltage of the outside circuit to aid in matching the impedance of this circuit with the circuit 32 which is accomplished by connecting the conductor to one of various taps from the secondary winding 44 of the transformer 4D.

Means is provided for constantly indicating the condition of the circuit consisting of a source of direct current, as at 53` and a supervisory circuit, one leg of which includes a milliammeter 54 and a variable resistance 55 connected at one side of' the condenser 50. The other leg of the circuit includes a relay 56, and is connected to conductor 46 on the opposite side of condenser 50. In this circuit. a hot feed is provided through the milliammeter 54, resistance 55, upper portion of conductor 4B, through the secondary winding 44. wire 45, fuse 41, through the outside circuit. including the coils of each of the speakers 49, through the lower portion of wire 46, relay 55, to the other side of the source.

The direct current in the supervisory circuit is required to travel throughout the entire outside circuit as described because of the condenser and the high resistance voltmeter 5I. The variable resistance is adjusted so that the amount of direct current flowing in the supervisory and outside circuit is somewhat greater than is necessary to energize the coil of relay 56 and hold the armature 60 in the up position in engagement with a contact 6I. The value r ani.' mu.

....4 h-mwwwm of this current will be indicated by the milliammeter 54. The supervisory circuit of each outside circuit is supplied with the same voltage and the relays 56 are all of the same construction. The purpose of establishing a greater ow of direct current in the supervisory circuit than is necessary to properly energize the relays 56 is to permit all of the supervisory circuits to be adjusted so that the reading on each of the milliammeters 54 is the same. For example, each oi the relays 56 may require six milliamperes to maintain the armature 60 in engagement with the contact 6l, but all of the supervisory circuits are adjusted to provide a ow of ten milliamperes therein. Accordingly, the operator at headquarters, or the central station, need only remember that the milliammeter in each supervisory circuit should indicate ten. This is in line with the general arrangement of the apparatus, such as the switches, etc., to render the operation of the system in the most simple form. The resistance of the voltmeter and resistances 52 is sufciently high to prevent a iiow of current to properly energize relay 56. Accordingly, if there is an open circuit at any point in the outside circuit, including the loud speakers 49 and the secondary winding 44 of the transformer, relay 56 will become deenergized and armature 60 will drop into engagement with a contact 65. The milliammeter 54 indicates at all times the condition of the outside circuit. For example, if any portion of the circuit should become short circuited, the reading on the meter 54 will rise in proportion to the condition of the short circuit.

The armature 60 is connected in one leg of a local circuit, and when in engagement with contact 6i, a circuit is completed through wire 62, green light 63, return conductor 64. If for any reason the outside circuit should become open, the current flowing through the supervisory circuit will diminish whereby relay 56 will permit armature 60 to drop into engagement with contact 65 completing a circuit through wire 65, red light 61, wire 64. Also, throughswitch 68 when in closed position, buzzer 69, conductor 64. When the outside circuit is in proper condition and current is supplied to the auxiliary signal circuit, the green light 63 is constantly displayed. However, if the outside circuit becomes open, the green light is extinguished, the red light displayed, and buzzer 69 energized, thus giving the operator a visual and audible signal that the outside circuit has become open and the operator can immediately inform the maintenance department oi this defect.

Provision is also made to test each outside circuit to ground. This feature of the system includes a battery, or other source of direct current 10, to one side of which is connected an ohmmeter 1i which in turn is connected to ground, as indicated at 12. The opposite side of the battery is connected to a conductor 13 through a variable resistance 14. The conductor 13 is connected to a rotatable switch blade 15 which may be successively moved into engagement with a plurality of contacts, each of which is connected to one leg of one of the outside circuits. For example, contact 16 is connected to conductor 45 through wire 11. Contact 18 is connected to wire 46 through wire 19.

When switch blade 15 is moved into engagement with contact 16, a circuit is completed through wire 11, wire 45 to ground, if any portion of the circuit is grounded, from ground,

through wire 12, ohmmeter 1i, to the other side of the source. If the circuit is grounded, the ohmmeter 1I will indicate the condition or extent of this defect. The meter 1l is of the type which may be adjusted for a zero reading on any particular circuit, and for the purpose of adjusting the ohmmeter a shunt circuit 85 is employed including a push button switch 8i, the opposite side oi which is connected to ground.

The line transformer 49, voltmeter 5i, condenser 56, and lightning arrester 48 of each outside circuit are located at headquarters. The broken line portions 82 of the outside circuits indicate that these circuit-s extend outwardly from headquarters, and the broken line portions 83 indicate that these circuits extend to one or more fire stations in each of which the loud speakers 49 are located. Conductors in the cables of the fire alarm system already installed are employed for the wires 45, 46 of the outside circuits.

It will be observed that the system described is economical to install and has been found highly eiiicient in use. Due to the novel arrangement of the supervisory circuit, the operator at headquarters is constantly advised as to the condition of the outside circuits. Heretofore, the condition oi' the outside circuits was ascertained only by periodic tests and infrequently these circuits would become defective without the operator being advised as to the existence of the defeet. The system has been found to be particularly advantageous over the conventional fire alarm system in that the operator can immediately communicate any information to all persons present in each fire station.

What I claim is:

1. A re alarm signal system of the type described comprising a voice current amplifier located at the central station and having a plurality of output circuits for 'the transmission of voice signals, each of said output circuits extending to a plurality of fire stations, a loud speaker arranged in each of said fire stations and said speakers being connected in series in said circuit, each output circuit including means operable to control the level of the voice signal lin said circuit, and means for varying the impedance of said circuit, a condenser connected in one leg of each output circuit, an indicating circuit connected in shunt with said condenser and being connected to a source of direct current, a variable resistance connected in said indicating circuit and operable to vary the current flowing therein, said indicating circuit also including a milliammeter operable to indicate at all times the direct current ilowing in said indicating circuit and said output circuit, a relay connected in said indicating circuit, a signal circuit connected to a source of current and being connected through the contacts of said relay and including two signals, said relay being operable to cause the signal circuit to give one of said signals when the direct current flowing in the indicating and output circuits is above a predetermined value, and being operable to give the other one of said signals when the direct current in said indicating and output circuits falls below said predetermined value, said milliamrneter and relay being operable without interference with the transmission of voice signals over said output circuit, and a volume indicating means connected across the legs of said out-put circuit and being operable to indicate the level of the voice signals on said circuit without interference with the direct current flowing in said indicating and output circuits. l

2. A re alarm signal system of the type described comprising a voice current amplifier located at the central station and having a plurality of output circuits for the transmission of voice signals, each of said output circuits extending to a plurality of re stations, a loud speaker arranged in each of said nre stations and said speakers being connected in series in said circuit, each output circuit including means operable to control the level of the voice signal in said circuit, and means for varying the impedance oi' said circuit, a condenser connected in one leg of each output circuit, an indicating circuit connected in shunt with said condenser and being connected to a source of direct current, a variable resistance connected in said indicating circuit and operable to vary the current flowing therein, said indicating circuit also including a miiliamrneter operable to indicate at all times the direct current :lowing in said indicating circuit and said output circuit and without interference with the transmission of voice signals over said output circuit.

3. A re alarm signal system of the type de scribed comprising a voice current ampliiier located at the central station and having a plurality of output circuits for the transmission of voice signals, each of said output circuits extending to a plurality of iire stations, a loud speaker arranged in each of said iire stations and said speakers `being connected in series in said circuit, each output circuit including means for varying the impedance of said circuit, a condenser connected in one leg of each output circuit, an indicating circuit connected in shunt with said condenser and being connected to a source of direct current. a variable resistance connected in said indicating circuit and operable to vary the current owing therein. said indicating circuit also including a milliammeter operable to indicate at all times the direct current flowing in said indicating circuit and said output circuit without interference with the transmission of voice signals over said output circuit.

4. A tire alarm signal system of the type described comprising a voice current amplier located at the central station and having an output circuit for the transmission of voice signals, said output circuit extending to a plurality of re stations, a loud speaker arranged in each of said fire stations and said speakers being connected in series in said circuit, a condenser connected in one leg of said output circuit, an indicating circuit connected in shunt with said condenser and being connected to a source of direct current, a variable resistance connected in said indicating circuit and operable to vari,r the current iiowing therein, said indicating circuit also including a milliammeter operable to indicate at all times the direct current iiowing in said indicating circuit and said output circuit without interference with the transmission of voice signals over said output circuit.

HAROLD O. QUICK. 

